This is the first component of the elongase, a microsomal protein
complex responsible for extending palmitoyl-CoA and stearoyl-CoA (and
modified forms thereof) to very-long-chain acyl CoAs.

Multiple forms exist with differing preferences for the substrate,
and thus the specific form expressed determines the local composition
of very-long-chain fatty acids.

For example, the FAE1 form from the plant Arabidopsis thaliana
accepts only 16 and 18 carbon substrates, with oleoyl-CoA (18:1)
being the preferred substrate, while CER6 from the same plant prefers
substrates with chain length of C(22) to C(32).